Process of polishing and finishing limestone, marble, &amp;c.



No. 774,121. PATENTED NOV. 1, 1904. C. H. WBIGELT.

PROCESS OF POLISHING AND FINISHING LIMESTONE, MARBLE, 6m.

APPLICATION FILED JAN. 26, 1903.

NO MODEL.

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U ITED STATES Patented November 1, 1904.

PATENT OFFICE.

CURT HEINRICH WEIGELT, OF BERLIN, GERMANY.

PROCESS OF POLISHING AND FINISHING LlMESTONE, MARBLE, 8L0.

SPECIFIGATION forming part of Letters Patent No. 774,121, dated November1, 1904.

Application filed January 26, 1903.

T 0 all whom, it may concern:

Be it known that I, CURT HEINRICH WEI- GELT, professor, a subject of theGerman Emperor, residing at 8 Pariserstrasse, Berlin, Germany, haveinvented new and useful Improvements in Processes of Polishing andFinishing Limestone, Marble, and the Like, of which the following is aspecification.

My invention relates to a process for polishing and finishing limestone,marble, and the like in which highly-diluted acids are used.

The polishing of stone is generally intended to give it a smooth brightsurface, rendering it better able to resist atmospheric influences andalso improving its appearance. The rough surfaces produced by thecutting or sawing of blocks of stone, owing to the unevenness of theirsurface, offer a great surface for the action of the air. If the unevenrough portions are removed, the surface exposed to the action of theatmosphere becomes smaller and the stone is rendered more durable.Hitherto this has been effected by mechanical grinding or polishing. Thesurfaces to be polished were sharply rubbed with a piece of stone of thesame kind, some of the dust produced during the sawing being interposedbetween the two surfaces. The larger uneven portions were thus removed,while the smaller ones were removed by means of emery or fine sand, andthe surface rendered perfectly smooth by polishing mediums, generallyoxid of iron. This treatment of stone required much labor and time.

By means of the present invention the same object is attained in a muchshorter time and the polish produced, whatever be the shape of thestone, is much superior to that attained by the ordinary polishingprocesses. The removal of roughness is effected according to thisprocess in a chemical way. Marble, more particularly certain kinds ofcarbonate stones the appearance of which is scarcely improved by theordinary polishing, is rendered by this process so attractive that itmay be used for decorative purposes in buildings and for artisticpurposes. For instance, Ruders- Serial No. 140,655. (No specimens.)

dorfer limestones if etched with hydrochloric acid of a strength of 1.5per one thousand take a very nice appearance.

The main feature of this invention consists in producing on the stone tobe polished a perfectly smooth surface without any hand labor. This is agreat improvement, especially as it at the same time enables even convexor projecting surfaces to be polished in a uniform manner. An essentialcondition for the proper carrying out of the polishing process is thecontinuous removal of the gas-bubbles generated on thepolishing-surface. If they are not removed at once, they cover thesurface to be polished, and thus prevent any further action of theacids. The surface then becomes covered with pits, spots, or stripes.The removal of the bubbles is effected by keeping the acid in continualmovement. The movement of the liquid causes the bubbles generated to becontinuously removed. Anther method of removing the bubbles would be tocarry on the process in a vacuum. Owing to the vacuum, the bubbles growrapidly and are drawn to the surface of the liquid, the latter thenbecoming agitated in the same way as water does when boiling.

In the accompanying drawing the figure shows a practical manner ofcarrying on the process with a vacuum.

In the drawing a vessel 0 is employed which is capable of being closedby a cover Z), so as to render the same practicallyair-tight. The edgesof the cover are drawn tightly to the walls of the vessel by screws 0for the purpose of securing such an air-tight joint. The vessel a isprovided with any suitable supports arranged interiorly thereof forholding the stone f therein. In treating a stone the vessel is usuallyfilled about one-half full with diluted acid. From the upper part of thevessel (4 is extended a pipe cl, which connects the vessel with thecylinder of an air-pump e. The pump may be of any usual or desired typeand when set into operation continuously draws ofi the developed gasesin the casing, thus tending to maintain a vacuum in the or perfectlysmooth, according to the length of time of immersion. Care must be takento keep the bath in a state of continuous movement in order that all thesurfaces exposed to the action of the acid should become uniformlyetched. This movement of the bath can be effected in various Ways. If itis desired to have at some points a deep or relieflike appearance or ifit is desired to have portions more or less highly polished, then theycan be covered during the Whole process or part by any substance Whichis insoluble in the acid.

Having now particularly described and ascertained the nature of my saidinvention and in What manner the same is to be performed, I declare thatWhat I claim is The process of producing a glazed or finished surfaceupon carbonate stone, consisting in subjecting the surface to the actionof dilute hydrochloric acid and agitating the same to preventgas-bubbles from continuing on said surface, the operation being carriedon in a vacuum for rendering the result of the process more perfect.

In testimony WhereofI have signed my name to this specification in thepresence of tWo subscribing Witnesses.

CURT HEINRICH \VEIGELT.

Witnesses WoLD EMAR HAUPT, HENRY HAsPER.

